Field of the Invention
The present invention relates to a sign information output apparatus for detecting a sign based on a captured image signal from an image capturing unit and outputting sign information representing the type of sign.
Description of the Related Art
Heretofore, there has been known a device for use on a vehicle, which detects a sign near a road based on an image signal from an image capturing unit, and outputs sign information representing the type of sign. Since this type of known device captures a sequence of images while the vehicle is being driven, the scene around the vehicle, which is represented in the captured images, may change at every moment. The device preferably performs a control process for causing the sign information output at the present time to fully follow the scene as it changes. Alternatively, the device may perform a control process such that previous content, which differs from sign information that exists in a scene at the present time, is not output as erroneous sign information.
For example, U.S. Patent Application Publication No. 2012/0046855 discloses a method of gradually decreasing the display intensity (representing an aging status) of sign information based on a travel state, including at least one of a traveled distance, an elapsed time, and a vehicle speed.
German Patent No. 102004042382 discloses a device for judging whether a vehicle is making a turn, and disabling display of sign information if an amount of steering or a radius of curvature of the turn exceeds a threshold value.